Pilot light structure for electromagnetic switch



Aug. 30, 1966 A. w. SCHUBRING PILOT LIGHT STRUCTURE FOR ELECTROMAGNETIC SWITCH 2 Sheets-Sheet 1 Filed July 20, 1965 INVENTOR.

A LL/N W. SCHUBR/NG A. W. SCHUBRING Aug. 30, 1966 PILOT LIGHT STRUCTURE FOR ELECTROMAGNETIC SWITCH Filed July 20, 1965 a Sheets-Sheet 2 INVENTOR.

ALL/N WSCHUBR/NG VFW F/EE r 3,270,164 Patented Augu t 9 1966 3,270,164 PILOT LIGHT STRUCTURE FOR ELECTRO- MAGNETIC SWITCH Allin W. Schubring, Milwaukee, Wis., assignor to Square D Company, Park Ridge, 11]., a corporation of Michigan Filed July 20, 1965, Ser. No. 473,294 6 Claims. (Cl. 335103) is connected in parallel with the magnet coil of the starter.

These prior structures were inherently deficient in several respects in that even if the magnet coil failed, or if the coil was energized and the armature or other parts of the starter prevented the contacts from moving to a circuit closing position, the pilot light would be energized. Ad ditionally, as coils having different voltage ratings are frequently used, a large variety of lights having dilierent ratings were required to be inventoried. The foregoing deficiencies in the prior art structures were overcome by Joseph J. Gribble in a structure disclosed in US. Patent No. 3,146,325, filed April 17, 1962 and issued August 25, 1965, which patent has been assigned to the assignee of the present invention.

The present invention relates to an improvement in the structures used in the Gribble Patent 3,146,325 and includes a pilot light assembly which is formed of two unitary structures which may be readily installed and removed from a starter without requiring tools for connecting and disconnecting wires and which will provide unimpaired access to the wire connecting terminals of the starter when a pilot light structure is removed from a pilot coil structure which provides the energizing current for the pilot light.

As was disclosed in the Gribble Patent 3,146,325, the source of power for the pilot light is provided by a secondary winding or pilot coil arranged in a closed circuit with the pilot light and in inductive relation to the magnetic motor coil so that an induced alternating voltage is provided in the circuit to the pilot light so long as the magnetic motor coil is energized by alternating voltage from its power source.

Generally, the magnet, armature and coils of contactors and starters are designed to produce a preselected flux and the magnet coil is modified to produce the preselected flux at the various different voltages at which the contactor is required to operate. Thus as the flux density in the magnet for an entire line of contactors is predetermined and constant for all voltage at which they are to be used, a pilot coil or secondary winding designed for a given flux density, and a pilot device operable by the voltage induced by that flux density, can be provided as a sub-assembly for installation in any one of the starters of the complete line.

Furthermore, since the pilot coil is energized by the fiux produced by the motor coil, should the motor coil or its source of voltage fail, the pilot light will be extinguished. Further, should the armature of the contactor stick in an open position, the flux passing through the pilot coil would thereby be appreciably reduced, with consequent reduction of the induced voltage, so that the pilot light would receive less voltage and thus burn dimly, in-

dicating that there is an inadequate voltagev across the magnet coil or that the electromagnet contactor itself is malfunctioning.

Since very little wattage is required for pilot lights, the secondary winding, or pilot coil, can be made in the shape of a relatively small, thin, and flat wafer, so it can be arranged conveniently at either end of the motor coil in surrounding relation to a portion of the central pole passing through the motor coil. When thus positioned, it can be made substantially coextensive radially with the end of the motor coil. An example of a structure with which it may be used is disclosed in an application of Joseph J. Gribble, Kenneth J. Marien, and Harold E. Whiting, Serial No. 473,299, filed concurrently herewith, which has been assigned to the assignee of the present invention.

It is an object of the present invention to provide an improved pilot light assembly structure for an electromagnetically operated switch, such as a starter, which includes a pilot light coil which may readily be installed on the magnet motor for the starter to operate according to the principles disclosed in the Gribble Patent 3,146,325, and an enclosure which detachably supports the pilot light externally of the housing for the starter so the enclosure may be readily removed to provide an unimpeded access 'to the wire connections to the starter.

A further object is to mount a pilot light on an outer wall of a starter with a mortise and tenon-likeconnection which will provide a secure detachable mounting for the pilot light on the starter.

' An additional object is to provide the pilot light coil structure with a coil portion which surrounds a portion of the magnet pole of a magnet motorfor the starter so the pilot coil will provide an output current when a magnet coil induces an alternating current flux in the magnet pole and to provide the pilot light coil with a base which has moldedprojections to provide a support'for pins which are electricallyconnected to windings of the pilot coil and extend through openings in a wall of the starter.

Another object is to provide a pilot light assembly which includes a :pilot light coil and a pilot light structure both of which are unitary structures which are electrically connected together without wires so the pilot light may be installed and removed with a minimum effort from an outer wall of a starter.

Further objects and features of the invention will-be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

FIG. 1 is an exploded view showing the parts of the pilot light assembly according to the present invention and certain of the parts of an electromagnetic switch to which the pilot light assembly may be applied. The par-ts of the pilot light assembly and switch are shown in perspective views.

FIG. 2 is a front plan view of the switch and pilot light assembly in FIG. 1 as assembled. a

FIG. 3 is a top plan view of the bulb support of the pilot light assembly shown in FIG. 1 with a portion of the 'bulb support housing broken away to illustrate constructional details of the support.

FIG. 4 is a side elevational view of the assembly in FIG. 1 with portions of the housing for the switch and bulb support broken away to illustrate constructional .details of the connection between the bulb support and the pilot light coil. V v

While the pilot light assembly as disclosed herein may be used with a variety of electromagnetically operated switches, it is particularly suited for use with an electromagnetic switch as disclosed in an application for US. Patent, Serial No. 476,299, concurrently filed herewith 3 which has been assigned by the inventors Joseph I. Gribble, Kenneth J. Marien and Harold E. Whiting to the assignee of the present invention.

The electromagnetic switch as shown in the Gribble et a1. application includes a base 12 which supports a housing 14. The base 12 is secured to a mounting plate 16 for mounting the switch 10 on a panel and supports a plurality of spaced pairs of stationary contacts, not shown, which are each connected to a terminal 20. The terminals 20, which are arranged to clamp a bared end of a wire conductor, not shown, are spaced along a front wall 22 and a rear wall 24 of the switch 10 between a bottom wall 26 of the base 12 and top edge 28 of the housing 14. The housing 14 has a cavity 30 therein which is open at the top edge 28 wherein a magnet motor 32 is positioned. As most clearly shown in FIG. 1, the magnet motor has an armature 34, a magnet coil 36 and a magnet pole 38. .The magnet coil has a toroidal shaped coil winding, not specifically shown, encapsulated in a molded housing 40 which has a flat end 42 facing the front wall 22 and a passage 44 extending perpendicular from the end 42 through the housing 40 and the central opening of the coil winding. The housing 40 has a pair of ears 45 thereon which are received in notches adjacent the top edge 28 of the side walls of the housing 14 to position the coil 36 in the cavity 30.

The magnet pole is preferably E-shaped to have a base portion 46 which is positioned between the flat end 42 and the front wall 22. Extending from the base portion 46 is a projection 48 which provides the center leg of E-shaped magnet pole which extends into the passage 44. A pair of parallel arms 50 which are formed on the opposite ends of the base portion 36 provide the remaining legs of the E-sha-ped magnet pole which extend to provide ends 52 which are located beyond a wall 54 of the coil housing 40 which is remote from the flat end 42.

The armature 34 preferably is T-shaped to have a base portion 56 from which extends a center leg 58 which is movable in the passage 44. The armature 34 has pole surfaces 60 which are moved into engagement with the ends 52 when the magnet coil 36 is energized to induce a magnetic flux in the magnet pole 38 to cause movement of the armature 34 from a deenergized position to an energized position wherein the pole surfaces 60 engage the ends 52. The coil housing 40 positions terminal screws 62 which are connected to the ends of the encapsulated coil winding and to suitable electric conductors for energizing the coil winding from a source of alternating current.

The pilot light coil structure 64 is formed of a unitary molded part which has a base portion 68 from which extends a thin, wafer-like portion 70 wherein a coil, not shown, which has a toroidal shape, is encapsulated. The wafer-like portion has an opening 72 which receives the projection 48 when a flat wall 74 on the base portion 68 and the wafer-like portion 70 is positioned adjacent the flat end 42 of the coil housing 40 and the base portion 46 of the magnet pole 38. The wafer-like portion 70 has a strengthening enlargement 76 adjacent its free end. The base portion 68 which is arranged to overlie and rest upon the upper surface of the magnet pole 38 when the magnet pole 38, the magnet coil 36 and the pilot light coil 64 are assembled. The base portion 68 has a pair of spaced projections 78 which extend through a pair of spaced notches or openings 80. The notches are formed in the front wall 22 along the top edge 28 and extend downwardly toward the base 12 in the housing 14. The projections 78 have outer ends 82 which are flush with the front wall 22. Projecting outwardly of the outer end 82 are pins 84 which are connected to the respective ends of the coil winding within the wafer-like portion 70 and project externally of the front wall 22.

The pilot light structure 86 is a unitary assembly which includes a rectangular enclosure 88, preferably formed of a molded insulating material, to have an open cavity 90 extending from a rear wall 92. Centrally located in a front wall 94 of the enclosure 88 is an opening 96 which extends into the cavity wherein a pilot light bulb 98 is received. The opening 96 is provided with slots to permit passage of a pair of bayonet lugs 100 on the base of the bulb 98. Secured adjacent the bottom wall of the cavity 90 are a pair of terminal members 102 and 103. The terminal member 102 has a portion 104 which surrounds the opening 96. The portion 104 is arranged to be engaged by the lugs 100 when the bulb 96 is installed in the opening 96. The terminal member 103 has a portion 105 which extends to engage a central terminal 107 of the bulb 98. The terminal members 102 and 103, which are preferably formed of resilient metal and insulated from each other, each have a pin engaging portion 106 generally extending at right angles to the portions 104 and 105. The pin engaging portions 106 are aligned with openings 108 in a bottom wall 110 of the enclosure 88 which are spaced to permit passage of the pins 84 into the cavity 90 when the enclosure 88 is positioned on the front wall 22. The pin engaging portions 106 each have an inwardly extending free end 112 extending from an apex 114 which projects outwardly from a curved pin receiving seat 116.

Also secured within the cavity 90 on opposite sides of the opening 96 are a pair of spring members 118 which have portions 120 extending to be pressed against the outer wall 22 when the enclosure 88 is mounted on the housing 14. The enclosure 88 and housing 14 are also provided with a means which forms a mortise and tenonlike connection for detachably mounting the enclosure 88 on the front wall 22. In the preferred embodiment shown, the mortise and tenon-like connection is provided by a mortise slot on the front wall 22 and a tenon-like tongue on the enclosure 88. The mortise-like slot is formed by a pair of spaced vertically extending ribs 122 which strengthen the front wall 22 of the housing 14. As shown, the ribs 122 have a top edge 124 spaced below the top edge 28 and have grooves 126 extending downwardly from the top edge 124 to a bottom stop 128. The grooves 126 in the respective ribs 122 face one another. The tenon-like tongue on the enclosure 88 is provided by a downwardly extending vertical wall which extends in the plane of the rear wall 92. The wall 130 is dimensioned to be loosely received in the grooves 126 and has a bottom edge which engages the stops 128 when the enclosure 88 is positioned on the front wall 22. Additionally, the wall 130 is strengthened by a portion 134 which extends downwardly at an angle from a bottom wall of the enclosure. The portion 134 is sized to be received between the ribs 122 when the enclosure 88 is mounted on the front wall 22.

A cover 132 for the switch 10 which engages the top edge 28 and portions of the coil housing 40 thereby positions the armature 34, the magnet coil 36, the magnet pole 38 and the pilot light coil 64 in the cavity 30 so the pins 84 extend externally of the front wall 22.

When the pilot light assembly is combined with the switch 10, the removal of the cover 132 permits the magnet motor 132 to be removed from the cavity 30. The magnet pole 38 is then separated from the magnet coil 36 by withdrawing the projection 48 from the passage 44. The pilot light coil 64 is then positioned on the magnet pole 38 with the projection 48 extending into the opening 72 and the base portion 68 resting upon the base portion 46. The magnet pole 38 with the assembled pilot light coil on the projection 48 is then reassembled with the magnet coil 36. When the magnet pole 38 and the magnet coil 36 are thus assembled, the flat wall 74 of the pilot light coil will engage the flat end 42 of the magnet coil. The entire magnet motor assembly with the pilot light coil thereon is then repositioned in the cavity 30 and the cover 132 is secured to the housing 14. When the foregoing assembly is completed, the pins 84 will project from the front wall 22. All that is required to complete the assembly of the pilot light with the switch is to position the enclosure 88 so that the vertical wall 130 is received in the grooves 126. When the enclosure 88 is thus positioned on the front wall 22, a slight pressure on the enclosure 88 toward the base 12 will cause the resilient arms of the pin engaging portions 106 to move inwardly as the bent portions of the free ends 112 are moved inwardly by the pins 84 to a position wherein the apex 114 is disposed below the pins 84 as the pins 84 are positioned in the spring seats 116. If it is desired to remove the pilot light structure 86 from the front wall 22, all that is required is that a slight pressure in the direction away from the base 12 be applied to the enclosure 88 which will permit the free ends 112 to pass out of engagement with the pins 84 and the mortise and tenon connection provided by the wall 130 and the grooves 126 to be separated.

When the pilot light assembly is installed in the switch 10 as described and the magnet coil 36 is energized from an outside current source, a magnetic flux will be induced in the magnet pole 38 which causes the armature 34 to be attracted to the pole and move to a position wherein the pole surface 60 of the armature engages the ends 52 of the magnet pole 38. The foregoing movement of the armature will cause the contacts of the switch to move into a bridging engagement with the contacts of the base of the switch 10. The alternating flux produced in the magnet pole 38 and the armature 34 by the magnet coil 36 induces an alternating voltage in the pilot coil 64 which is transmitted through the pins 84 and the terminal members 102 and 103 to energize the bulb so that the bulb remains lighted as long as the magnet coil 36 is energized.

In the event that the magnet coil 36 should he energized and the armature 34 should be prevented from moving to its energized position, the flux through the pilot light coil 64 will be less than when the armature is in the energized position. When this result occurs, a lesser voltage will be induced in the pilot coil 64 so that the bulb 98 will glow :with a less intensity so as to indicate a malfunction of the switch 10.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. An electromagnetic switch assembly comprising: a housing having an open cavity extending downwardly from an exposed top edge toward a base of the housing, a pair of spaced notches in a front wall of the housing extending downwardly from the top edge, a magnet motor positioned in the cavity, said magnet motor having: a magnet coil having a flat end facing the front wall portion of the cavity and a passage extending therethrough perpendicular to the flat end along an axis parallel to the top edge and perpendicular to the front wall, a magnet pole member having a base portion positioned between the coil and front wall and a portion projecting from the base portion into the passage, and an armature positioned at an end of the coil remote from the front wall and being in magnetic attractive relation to the magnet pole when the magnet coil is energized, a pilot light assembly comprising: a pilot coil structure and a pilot light structure, said pilot coil structure being a unitary structure having: a base portion resting on the base portion of the magnet pole member, a thin wafer-like coil portion extending from the base portion positioned between the dlat wall of the magnet coil and the base portion of the magnet pole, a passage in the wafer portion receiving the projection on the base portion of the magnet pole, a pair of spaced projections on the base portion of the pilot coil structure received in the notches and a pair of terminal pins electrically connected to the windings of the coil and projecting outwardly from the projections externally of the front (wall, said pilot light structure being a unitary structure having: an enclosure providing a cavity extending from a rear edge of the enclosure, means on the rear edge of the enclosure and the front wall of the housing providing a mortise and tenon-like connection for detachably mounting the pilot light structure on the front wall of the switch, a lamp socket extending from a front wall of the enclosure into the cavity, a pair of resilient connectors within the enclosure cavity electrically connected to a pair of terminals of the lamp socket, said connectors being engageable with the pins when the enclosure is mounted on the front Wall of the switch and a cover for the housing of the switch, said cover being eng-ageab-le with portions of the magnet coil for positioning the magnet motor and the pilot coil structure in the switch cavity.

2. A pilot light assembly for an electromagnetic switch comprising a pilot coil structure and a pilot light structure, both of said structures being unitary and detachable from the electromagnetic switch, said switch having: a housing having an open cavity extending from an exposed top edge toward a bottom wall of the housing, a plurality of spaced terminal connectors extending outwardly of a front wall of the housing intermediate the top edge and the bottom wall, a magnet motor positioned in the cavity, said magnet motor including: a magnet coil having a flat end wall and a, passage extending therethrough perpendicular to the flat end wall, a magnet pole member having a base portion disposed at the flat end wall and a projection extending from the base portion into the passage, and an armature positioned at an end of the coil remote from the flat end wall and being in magnetic attractive relation to the magnet pole when the magnet coil is energized, said pilot coil structure having a base positioned in the cavity, a pair of spaced pins extending from the base outwardly through a pair of spaced openings in the front wall adjacent the top edge, and a thin wafer-like coil portion extending from the base, said wafer-like coil portion being positioned between the flat end wall and the base portion of the magnet pole and having a passage in the wafer-like portion receiving the projection, said pilot light structure having: an enclosure providing a cavity extending from a rear edge of the enclosure, means on the rear edge of the enclosure and front wall of the housing providing a mortise and tenon-like connection for detachably mounting the enclosure on the front Wall when the enclosure is moved in a downward direction along the front wall toward the bottom wall, a lamp socket extending from a front wall of the enclosure into the cavity, a pair of resilient connectors within the enclosure cavity electrically connected to a pair of terminals of the lamp socket and engageable with the pins when the enclosure is moved in the downward direction and mounted on the front wall, and a resilient means within the enclosure cavity engageable with the front wall of the housing for maintaining the mortise and tenon-like connection between the enclosure and front wall whereby the pilot light structure is removable from the front wall of the housing to provide access to the terminal connectors and a cover for the housing positioned on the top edge to close the cavity, said :cover being engageable with portions of the magnet motor for positioning the pilot coil structure and magnet motor in the cavity within the housing.

3. The combination as recited in claim 2 wherein the mortise and tenon-like connection is provided by a pair of spaced ribs on the front wall which ribs have grooves therein which terminate a predetermined distance from the top edge to provide a stop for a pair of oppositely extending ledges which extend from the enclosure.

4. The combination as recited in claim 2 wherein the resilient connectors engage the spaced pins with a snap action connection to resiliently maintain the enclosure on the front wall of the hon-sing.

5. The 'eombination as recited in claim 2 wherein the warfer-like coil is formed :as a molded part to have projections extending through the openings in the front wall and the pins are embedded in the projections.

6. The combination as recited in claim 1 (wherein a plurality oi terminals are spaced in a plane parallel to the top edge along the front wall and the pilot light structure When removed provides a free access to the terminals.

References Cited by the Examiner UNITED STATES PATENTS 3,146,325 10/1964 Gribble 200-87 BERNARD A. GIDHEANY, Primary Examiner.

I. J. BAKER, Assistant Examiner. 

1. AN ELECTROMAGNETIC SWITCH ASSEMBLY COMPRISING: A HOUSING HAVING AN OPEN CAVITY EXTENDING DOWNWARDLY FROM AN EXPOSED TOP EDGE TOWARD A BASE OF THE HOUSING, A PAIR OF SPACED NOTCHES IN A FRONT WALL OF THE HOUSING EXTENDING DOWNWARDLY FROM THE TOP EDGE, A MAGNET MOTOR POSITIONED IN THE CAVITY, SAID MAGNET MOTOR HAVING: A MAGNET COIL HAVING A FLAT END FACING THE FRONT WALL PORTION OF THE CAVITY AND A PASSAGE EXTENDING THERETHROUGH PERPENDICULAR TO THE FLAT END ALONG AN AXIS PARALLEL TO THE TOP EDGE AND PERPENDICULAR TO THE FRONT WALL, A MAGNET POLE MEMBER HAVING A BASE PORTION POSITIONED BETWEEN THE COIL AND FRONT WALL AND A PORTION PROJECTING FROM THE BASE PORTION INTO THE PASSAGE, AND AN ARMATURE POSITIONED AT AN END OF THE COIL REMOTE FROM THE FRONT WALL AND BEING IN MAGNETIC ATTRACTIVE RELATION TO THE MAGNET POLE WHEN THE MAGNET COIL IS ENERGIZED, A PILOT LIGHT ASSEMBLY COMPRISING: A PILOT COIL STRUCTURE AND A PILOT LIGHT STRUCTURE, SAID PILOT COIL STRUCTURE BEING A UNITARY STRUCTURE HAVING: A BASE PORTION RESTING ON THE BASE PORTION OF THE MAGNET POLE MEMBER, A THIN WAFER-LIKE COIL PORTION EXTENDING FROM THE BASE PORTION POSITIONED BETWEEN THE FLAT WALL OF THE MAGNET COIL AND THE BASE PORTION OF THE MAGNET POLE, A PASSAGE IN THE WAFER PORTION RECEIVING THE PROJECTION ON THE BASE PORTION OF THE MAGNET POLE, A PAIR OF SPACED PROJECTIONS ON THE BASE PORTION OF THE PILOT COIL STRUCTURE RECEIVED IN THE NOTCHES AND A PAIR OF TERMINAL PINS ELECTRICALLY CONNECTED TO THE WINDINGS OF THE COIL AND PROJECTING OUTWARDLY FROM THE PROJECTIONS EXTERNALLY OF THE FRONT WALL, SAID PILOT LIGHT STRUCTURE BEING A UNITARY STRUCTURE HAVING: AN ENCLOSURE PROVIDING A CAVITY EXTENDING FROM A REAR EDGE OF THE ENCLOSURE, MEANS ON THE REAR EDGE OF THE ENCLOSURE AND THE FRONT WALL OF THE HOUSING PROVIDING A MORTISE AND TENON-LIKE CONNECTION FOR DETACHABLY MOUNTING THE PILOT LIGHT STRUCTURE ON THE FRONT WALL OF THE SWITCCH, A LAMP SOCKET EXTENDING FROM A FRONT WALL OF THE ENCLOSURE INTO THE CAVITY, A PAIR OF RESILIENT CONNECTORS WITHIN THE ENCLOSURE CAVITY ELECTRICALLY CONNECTED TO A PAIR OF TERMINALS OF THE LAMP SOCKET, SAID CONNECTORS BEING ENGAGEABLE WITH THE PINS WHEN THE ENCLOSURE IS MOUNTED ON THE FRONT WALL OF THE SWITCH AND A COVER FOR THE HOUSING OF THE SWITCH, SAID COVER BEING ENGAGEABLE WITH PORTIONS OF THE MAGNET COIL FOR POSITIONING THE MAGNET MOTOR AND THE PILOT STRUCTURE IN THE SWITCH CAVITY. 